Among the currently provided TRS, WCTS is one type of developed CTS (Captioning Telephone Service). WCTS is a relay service that transfers voice traffic of the other user together with caption traffic literated at a relay center to the handicapped and transfers voice traffic of the deaf person who can speak to the other user as it is. Said relay service transfers voice data through existing wire or wireless voice communication network and conveys captioned data through data network. Also said relay service, regarding the way for a deaf person who can speak to call, executes special application program at a device connected to internet, enters the calling number and the handicapped person's own number, and then transfers the numbers to the relay center. After this process, said relay center calls a relay agent, person called and a deaf caller who can speak and forms the voice communication path. For that reason, there is serious inconvenience that the deaf caller who can speak should receive the call from the relay center even though he is the caller himself.
And, regarding the way for a non-handicapped person to call the dead person who can speak, the non-handicapped person cannot directly press the number of the handicapped person. He should call the relay center and wait for ARS or relay agent to answer. After ARS or relay agent answers, the non-handicapped person must enter the number of handicapped by using DTMF (Dual Tone Multiple Frequency) or directly dictate the number. For this reason, the process is very complicated and inconvenient. Also there is burden on the side of handicapped person to expose his handicap because he should give the number of relay center when he gives out his telephone number.
Regarding the mobile terminal of the deaf person who can speak, due to the advancement in mobile communication technology, the mobile terminal can use CTS by executing mobile VoIP (mVoIP) based program in the smart phone. However, for the management of the mobility of terminal, frequent communication with mobile communication packet network is required, which causes the battery consumption problem. Upon reception and transmission of call, special program user interface is required. This makes impossible the use of distinctive smart phone service, which is dialer function. The loss of receipt call on account of absence of function of paging in the mobile communication packet network is another problem.